1. Field of the Invention
This invention relates to an apparatus for opening lateral scores in a moving glass sheet.
2. Discussion of the Prior Art
In the prior art, there are taught various apparatuses for opening lateral scores in a glass sheet. "Lateral scores" as the term is used herein are scores, score fractures or fissures in the glass that extend between the side edges of the glass sheet as it advances along an article movement path.
U.S. Pat. No. 662,924 teaches a glass cutting machine having a half table. In general, a sheet of glass is positioned and clamped on the half table and a score is imposed on the glass sheet to coincide with the junction line of the half table. Thereafter the half tables are pivoted away from each other to open the score.
The apparatus for cutting glass taught in U.S. Pat. No. 662,924 is not adaptable for opening lateral scores in moving glass sheets and is only applicable for opening a lateral score in a stationary single sheet.
U.S. Pat. Nos. 3,141,589 and 3,175,745 teach a glass breaking apparatus that includes a horizontal conveying section and a separate inclined conveying section. A glass sheet is moved along the horizontal section as the lateral scores are opened to sever the sheet. Thereafter, the leading edge of the severed glass sheet tilts onto the inclined conveying section.
The drawback of the scoring apparatuses of the type taught in U.S. Pat. Nos. 3,141,589 and 3,175,745 is that the leading edge of the sheet engages the inclined conveying section. Under certain conditions, flares remain on the cut edge of the severed glass sheet. When these flares engage the inclined conveying section, they break off and leave chips of glass on the conveyor. These chips of glass may scratch subsequently severed glass sheet.
U.S. Pat. No. 3,372,847 teaches a glass breaking apparatus. In general, a scored glass sheet is advanced by conveyor rolls along a movement path having an upwardly inclining path portion and a downwardly inclining path portion. A holddown roll is mounted over each of the inclining path portions and a roll is rotatably mounted above the apex of the movement path and operatively connected to vibrating facilities. When the lateral score in the sheet is at the apex of the path, a bending moment is applied to the glass as the roll is vibrated to open the score and sever the sheet.
The drawback of the apparatus taught in U.S. Pat. No. 3,372,847 is the additional vibratory equipment needed to open the score and sever the sheet. Further the apparatus is limited to opening lateral scores spaced apart a distance greater than the distance between adjacent rolls to prevent the severed sections from falling between the rolls.
U.S. Pat. No. 3,494,523 also teaches a device for fracturing scored glass sheets. In general, a flexible endless belt is stretched over a plurality of pulleys. A fixed spring sheet bears against the belt to define a movement path. The spring sheet and belt are flexed to provide a curved path portion to applying bending stress to open the lateral scores and sever the sheets.
Although the fracturing device disclosed in U.S. Pat. No. 3,494,523 is acceptable for opening lateral scores in moving sheets, it has limitations. More particularly, the curved path is defined by a spring member and a belt portion between which the glass sheet is moved. Deflecting the belt and spring member applies a bending moment to open the scores. In the instance where adjacent scores are spaced a great distance apart, the glass sheet binds in the space between the belt and the spring. Reducing the curvature to permit the passing of the glass sheet reduces the stress applied to the scores. In certain instances, e.g., for glass sheets having a thickess of about 1/2 inch (1.27 centimeters) the bending moment force may not be adequate to open the scores and sever the sheet.
In U.S. Pat. No. 3,517,869, it is taught to advance a glass sheet in its own plane between a pair of conveyor members initially aligned in a common plane with a second pair of conveyor members. The first pair of conveyor members is tilted and the sheet having lateral scores is advanced over a breaking roll and into its original plane of advancement onto the second pair of conveyor members. The sheet is broken into segments by the breaking roll and conveyed beyond the breaking roll by the second pair of conveying members as the first pair of conveying members is tilted back to its original position to receive the next sheet.
The drawback of the apparatus of U.S. Pat. No. 3,157,869 is that it is not usable for opening scores in fast moving sheets. This is because the first conveyor section that receives the sheet is tilted out of the receiving plane and remains in that position until the scores in the sheet are opened. In the tilted position, subsequent sheets cannot be moved onto the first conveyor section.
It would be advantageous to provide an apparatus for opening lateral scores in a moving sheet that does not have the limitations of the prior art snapping apparatus.